<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
     .div{
         width: 400px;
         height: 400px;
         margin:50% auto;
         /*margin: 0 50%;*/
         background-color: pink;
     }
</style>
<body>

<div class="div">

</div>
</body>
</html>